The primary objective of this project is to correlate the morphological, biomechanical, and biochemical properties of the ligament healing processes in a model synovial joint. Clinicians often need to make decisions regarding the treatment of knee injuries involving damage to more than one ligament. However, the preferred treatment for one knee ligament may be very different from that for another knee ligament. Recently, isolated medial collateral ligament (MCL) injuries have been treated non-operatively, whereas surgical reconstruction is frequently recommended for a torn anterior cruciate ligament (ACL). Frequently, injuries involve both the MCL and ACL, and yet, the influence of ACL reconstruction on MCL healing has not been defined, nor has the effectiveness of additional treatment regimens. The suboptimal treatment of these combined injuries generally leads to persistent joint instability. Although various treatments have been recommended, there are few objective comparisons of their results. Therefore, we have designed studies to evaluate the influence and interrelationship of variables such as ACL transection, ACL reconstruction, daily valgus loading programs, and growth factors on the MCL healing process. We also will evaluate the functional role of the MCL and how its injury and subsequent healing would change the kinematics of the knee joint. The injury model will include rupture of the MCL; severely damaging both the ligament midsubstance and its insertions to bone. The time course of MCL healing up to one year will be studied morphologically, biomechanically, and biochemically. The correlated data obtained from these interdisciplinary approaches should permit us to better understand the healing processes of both the MCL substance and the ligament insertions to bone. We anticipate that such knowledge will ultimately lead to improved treatment for patients with combined MCL+ACL injuries.